Effect of anticoagulant agents on prostacyclin (PGI2) generation from arterial wall

Abstract

Prostacyclin (PGI2) has been reported to be a labile but potent inhibitor of platelet aggregation and a powerful vasodilater. In this report, the effect of anticoagulant agents on PGI2 generation from rat aorta was investigated.PGI2 activity was assayed by the inhibition percentage of ADP induced platelet aggregation. The aortic ring was incubated in 0.05M Tris HCl buffer (pH 7.5) containing Heparin, Dextran Sulfate (DS) or Low Molecular Weight Dextran (LMD) at room temperature for 10min. The supernatant of this incubation medium was added to human PRP and platelet aggregation was induced by ADP. Since this activity was disappeared by the inhibitor of cyclooxygenase and PGI2 synthetase, it was confirmed to be PGI2 activity.PGI2 generation from rat aorta was accelerated by the addition of DS and LMD but not by Heparin. Moreover, the aorta of rat injected previously with DS or LMD demonstrated the accelerated PGI2 generation, while Heparin injection had no effect on PGI2 generation.These results indicated that the acceleration of PGI2 generation from rat aorta which was induced by these agents may be involved in the mode of action of them. That is, these agents are effective not only on the inhibition of platelet aggregation but also on the acceleration of PGI2 generation from vessel wall. These activity may be responsible to be important in the regulatory mechanism of microcirculation and the prevention of thrombosis formation.